rename wayland session desktop file

This ensures all display managers provide both the wayland and x11 sessions to
the user.
- when two different desktop files have the same desktop-id, they're merged.
- gdm uses this to implement fallback from wayland -> x11, in case of a crash.
- this behavior isn't standardized since fdo doesn't really define the desktop
  session files, so there's some variation.

Providing the files under different names should work everywhere.  This is
summarized from https://gitlab.gnome.org/GNOME/gdm/-/issues/898

data/session/wl/meson.build

@@ -2,8 +2,8 @@ desktop_config = configuration_data()
 desktop_config.set('prefix', dir_prefix)
 desktop_config.set('VERSION', e_version_rev)
 e_desktop = configure_file(
-  input         : 'enlightenment.desktop.in',
-  output        : 'enlightenment.desktop',
+  input         : 'enlightenment-wayland.desktop.in',
+  output        : 'enlightenment-wayland.desktop',
   configuration : desktop_config)
 
 if config_h.has('HAVE_WAYLAND') == true